Who devised for the first time,a method for measuring atmospheric pressure?

$A$ barometer kept in a stationary elevator reads $76 \ cm$. If the elevator starts accelerating upwards,the reading will be:

In a cylindrical container open to the atmosphere from the top,a liquid is filled up to a $10\, m$ depth. The density of the liquid varies with depth $h$ from the surface as $\rho(h) = 100 + 6h^2$,where $h$ is in meters and $\rho$ is in $kg/m^3$. The pressure at the bottom of the container will be: (Atmospheric pressure $P_0 = 10^5\, Pa$,$g = 10\, m/s^2$)

$A$ vertical off-shore structure is built to withstand a maximum stress of $10^9 \; Pa$. Is the structure suitable for putting up on top of an oil well in the ocean? Take the depth of the ocean to be roughly $3 \; km$,and ignore ocean currents.

$A$ pressure of $1 \,mm$ of mercury is equivalent to

During blood transfusion,the needle is inserted into a vein where the gauge pressure is $2000 \; Pa$. At what height (in $m$) must the blood container be placed so that blood may just enter the vein? (Density of whole blood,$\rho = 1.06 \times 10^{3} \; kg \; m^{-3}$,$g = 9.8 \; m \; s^{-2}$)